The perfect storm

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In many ways, Sunday's tornadic supercell was the perfect storm.

It was the "lead" supercell in a cluster of storms. That means it had an uninterrupted feed of moisture rich, warm unstable air into the southeast side of the storm. The lead storms in these supercell clusters have been identified as the ones to watch for tornadoes. They are spawned in the most favorable mesoscale environment for rotation and tornado production.

The classic "hook echo" near Coon Rapids marks the tornado's location.

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On the back side of this lead storm, cooler and more stable air wrapped in from the northwest. This "rear flank downdraft" disturbed the environment for other storms back to the west, and they did not become tornadic.

Though this tornado was a tragedy for Coon Rapids and Hugo, it was mild compared to what damage would have occurred if the storm was 10 or 15 miles to the south. That would have taken it right through the heart of the Twin Cities metro, and the death toll and injury numbers would have been much higher.

Sunday was also a major success for the Twin Cities NWS. With up to 20 minutes lead time, those who heeded the warnings had plenty of time to take cover.

PH